Sahih Adab al-Mufrad

Narrated from Sayyiduna Anas bin Malik (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) said: “Do not bear malice against one another, do not envy one another, do not boycott one another, and O servants of Allah! Be brothers to one another. It is not lawful for any Muslim to boycott his Muslim brother for more than three days. Do not speak ill behind each other's backs, and O servants of Allah, live as brothers among yourselves. It is not lawful for any Muslim to sever relations with his brother for more than three nights.”

It is narrated from the companion of the Messenger of Allah, Abu Ayyub (may Allah be pleased with him), that the Messenger of Allah (peace and blessings be upon him) said: "It is not permissible for a person to boycott his brother for more than three days. When they meet, both turn away from each other, and the better of the two is the one who greets first."

Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates from the Prophet (peace and blessings of Allah be upon him) that he said: "Do not harbor hatred among yourselves, do not envy one another, and do not act with hypocrisy. Be, O servants of Allah, brothers to one another."

Sayyiduna Anas (may Allah be pleased with him) reports that the Messenger of Allah (peace and blessings be upon him) said: "When two persons love each other for the sake of Allah, or he said, for the sake of Islam, then the first sin committed by either of them causes separation between them."

It is narrated from Hisham bin 'Amir Ansari, who was a cousin of Anas bin Malik and whose father was martyred on the day of Uhud, that he said he heard the Messenger of Allah (peace and blessings be upon him) say: "It is not permissible for a Muslim to cut off relations with another Muslim for more than three days. As long as both of them persist in this estrangement, they remain away from the truth. And whoever reconciles first, his initiative will be an expiation for his sin. If they die in this state of estrangement, they will never enter Paradise together. And if one of them greets the other and the other does not accept his greeting, then an angel responds to the one who greeted, and Satan responds to the one who refused. Whoever ends this situation first, his action will be an expiation for the previous mistake. And if both die in this state, neither of them will ever enter Paradise. And if one greets and the other refuses to accept the greeting, then an angel responds to the one who greeted, and Satan responds to the one who refused."

Narrated from Sayyidah Aisha (may Allah be pleased with her), she said: The Messenger of Allah (peace and blessings be upon him) said: "I know when you are angry and when you are pleased." I asked, "How do you know that?" He said: "Indeed, when you are happy, you say (when swearing an oath), 'Yes, by the Lord of Muhammad (peace and blessings be upon him),' and when you are angry, you say, 'Yes, by the Lord of Ibrahim.'" Sayyidah Aisha (may Allah be pleased with her) said: I replied, "Yes, O Messenger of Allah, it is just as you say. I only avoid mentioning your name."